Tsunami Detection System Nick Street, Project Engineer David Mould, Presenter.

Transcription

1 Tsunami Detection System Nick Street, Project Engineer David Mould, Presenter

2 Agenda 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface Unit - Transceiver 6. Satellite Modem Link 7. Data Examples 8. Acoustic telemetry overview 9. Q&A

3 Need for Tsunami Detection System As a result of the Boxing Day 2004 Tsunami the owner of Sonardyne, John Partridge, decided that Sonardyne should look to producing a Tsunami Detection System to help give early warning of a potential life and property damaging event.

4 System Overview The system consists of a seabed pressure monitoring transponder, a surface buoy with a data collection unit that passes the acoustic message to a satellite telephone system and then onwards to the shore base.

5 What Do We Need To Detect? At the Beach easy to detect but to late Nearing the coast, easy to detect but still to late In deep water very hard to detect against the natural sea surface movement, but this is the only option that gives enough early warning time

6 Tsunami Detection System Requirements Pressure sensor Detection Algorithm Acoustic Link Long battery life Release mechanism Floatation Satellite modem

7 Tsunami Detection Algorithm Based on NOAA algorithm Predicted pressure calculated from previous 3 hour history, using 10 minutes from each hour (adapted for slow wave) Detection criteria: C-O > threshold for 2 consecutive samples. - 3cm used for threshold. Spike filter single reading > 10cm ignored Detection threshold can be changed by acoustic command An Event can be forced or cancelled by acoustic command.

8 Tsunami Detection System 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface Unit - Transceiver 6. Satellite Modem Link 7. Data Examples 8. Acoustic Telemetry Overview 9. Q&A

9 Subsea Unit Tsunameter Based on instrumented survey transponder Compatt 5 Paroscientific Digiquartz pressure sensor Acoustic data link - High speed 1kb/s - Forward Error Correction (FEC) - Wideband technology Lithium battery pack 2 year operation Integral acoustic release Floatation collar Thousands of operational deployments Single pressure housing

10 Advantages of a Single Subsea Unit No requirement for level seabed No subsea cables and connectors Lighter easier deck handling In-house control over entire system Rapid modifications Simplified testing Re-use of existing parts Track record 1000 s deployments Proven battery life Engineering support

11 Tsunameter - Sensor Electronics Paroscientific Digiquartz sensor psi (6800m) range - Or 6000psi (4000m) range - Temperature compensated - Extremely high repeatability under stable thermal conditions Platinum Resistance Thermometer for sea water temperature Release motor Memory card

12 Tsunameter - Sensor Electronics Paroscientific Digiquartz sensor psi (6800m) range - Or 6000psi (4000m) range - Temperature compensated - Extremely high repeatability under stable thermal conditions Platinum Resistance Thermometer for sea water temperature Release motor Memory card

13 Tsunameter - Sensor Electronics Paroscientific Digiquartz sensor psi (6800m) range - Or 6000psi (4000m) range - Temperature compensated - Extremely high repeatability under stable thermal conditions Platinum Resistance Thermometer for sea water temperature Release motor Memory card

14 Tsunameter - Sensor Electronics Paroscientific Digiquartz sensor psi (6800m) range - Or 6000psi (4000m) range - Temperature compensated - Extremely high repeatability under stable thermal conditions Platinum Resistance Thermometer for sea water temperature Release motor Memory card

15 Tsunameter Deployment in the Bay of Bengal

16 Tsunami Detection System 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface Unit - Transceiver 6. Satellite Modem Link 7. Data Examples 8. Acoustic Telemetry Overview 9. Q&A

17 Surface Unit - Transceiver Lightweight - 9kg in water Low power - 1W at 24V Wideband signal technology Integral Li+ battery Armoured cable to buoy Optional acoustic baffle 5km+ acoustic range > Buoy mounted transceiver with side noise shield that connects to satellite telephone system

18 Tsunami Detection System 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface Unit - Transceiver 6. Satellite Modem Link 7. Data Examples 8. Acoustic Telemetry Overview 9. Q&A

19 Satellite Modem Link 2-way communication link Allows direct control of transceiver Allows acoustic commands to be sent to subsea unit - to alter set-up parameters - diagnostics - to Force or Cancel Events Not included in Sonardyne scope of supply

20 Tsunami Detection System 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface Unit - Transceiver 6. Satellite Modem 7. Data Examples 8. Acoustic Telemetry Overview 9. Q&A

21 Data Example - Acoustic SMS Messages Hourly pressure data 4 readings averaged over 15 minutes Hourly status data battery, sea water temp. SMS format (Sonardyne Messaging Service) for short text messages: Identifies data source address ASCII message delivered securely Pressure Log Status YMDHMS Type 1 (Hourly) P1 P2 P3 P4 SMS:0102, ;1,39866;1,40022;1,40157;1,40288 SMS:0102,0 V142,U019,B0,O0,T0,S+1550, SMS:0102, ;1,40394;1,40492;1,40569;1,40635 SMS:0102,0 V142,U019,B0,O0,T0,S+1550, Tpdr ID F/W Version % Used Battery Alarm Battery On Tilt Temperature Up to 128 ASCII characters for customer defined message

22 Data Example - Hourly Pressure Messages Acoustic data hourly message, data points every 15 minutes Raw abs. pressure (10Pa) :00 00:00 06:00 12:00 18:00 00:00 Date Time

23 Logged Data Analysis Raw abs pressure (Pa) Vertical scale: 1 div ~ 1cm Measured Predicted Diff (C-O) Simulated Event: measured vs predicted, data from memory card (Difference rebased to ) detection point detection threshold 09:20 09:30 09:40 09:50 10:00 3 cm

24 Data Recovery Tsunameter: Full Event Cycle Standard mode: Type 1 message containing 4 readings averaged over 15 minutes sent every hour Event mode: 1x Type 2 message containing 4 x 15s consecutive readings 2 before & 2 during Event) Extended reporting mode: 36x Type 3 messages containing10 readings, 30s apart (sent every 5 minutes) t- 60 t 0 t 60 t 120 t 180 t 240 Time (minutes)

25 Event - Data Recovery Tsunameter: records telemetered during Event Extended reporting mode: 36 x 10 x alternate 15s readings Event mode: 4 x 15s readings Key: t -2 t -1 t 0 t 2 t 3 Time (minutes) t 1 t 4 t 5 t 6 t 7 t 8 t 9 t 10 t 11 t 12 One acoustic message A single raw pressure value One reading made every 15 seconds

26 Acoustic Data from Plymouth Trial 30 Metres Tsunami C5 acoustic data: Plymouth Sept sent via SMS (vertical scale 1m/div) Another detection at 07: Unit recovered to surface Raw abs pressure (10Pa) Event detection at 01:08 starts rapid data telemetry for 180 minutes /09/ /09/ /09/ /09/ /09/ /09/2006

27 Sea Trial Data 600 Metres Sonardyne sea trial - 600m Absolute pressure (10Pa ~mm) /02/ /02/ /02/ /02/ /02/ /02/2007

28 NIOT Tsunami Buoy Locations Buoy TB10 which sent the following data

29 NIOT Battery Life Test Sonardyne data: Nicobar earthquake 25/07/07 Station: TB10-7 deg 1'N 87 deg 4'E Source: 7.08N 92.59E Magnitude Abs pressure (1mm ~ 10 Pa) Vertical scale ~10cm/div /07/ /07/ /07/ /07/ /07/ /07/ /07/2007 Real event caused NIOT to be concerned about battery life

30 The Event Two Hours Before Sonardyne data: Nicobar earthquake 25/07/07 Station: TB10-7 deg 1'N 87 deg 4'E Source: 7.08N 92.59E Magnitude Abs pressure (1mm ~ 10 Pa) Vertical scale ~1cm/div :30:00 21:45:00 22:00:00 22:15:00 22:30:00 22:45:00 23:00:00 23:15:00 23:30:00 23:45:00 00:00:00 00:15:00 00:30:00 The regular 15 minute interval logs that are sent once per hour Event data takes priority over 15 minute interval logs from the hour in which the event occurs, hence with event just before the hour the ¼, ½ and ¾ hour records are not sent

31 The Event - Post Event Data Sonardyne data: Nicobar earthquake 25/07/07 Station: TB10-7 deg 1'N 87 deg 4'E Source: 7.08N 92.59E Magnitude Abs pressure (1mm ~ 10 Pa) Vert. scale: ~1cm/div :00:00 23:10:00 23:20:00 23:30:00 23:40:00 23:50:00 00:00:00 00:10:00 00:20:00 00:30:00 00:40:00 00:50:00 01:00:00 Data points passed on by NIOT satellite phone system

32 The Event National Media Coverage

33 Tsunami Detection System - Requirements 1. Need for Tsunami Detection System 2. System Overview 3. Tsunami Detection System requirements 4. Seabed Unit - Tsunameter 5. Surface unit - Transceiver 6. Satellite Modem Link 7. Data Examples 8. Acoustic Telemetry Overview 9. Q&A

34 A Tone signal Single Frequency No modulation Defined duration

35 A Wideband Signal Single carrier Frequency Phase modulation to write data onto signal Phase changes identify code Large numbers of codes can be generated Not all are suitable for navigation due to correlation properties Known as Phase Shift Keying (PSK)

36 Correlation Processing - Tone Signal Incoming Signal Stored Replica Reasonable Timing Detection Threshold Correlation Response

37 Correlation Processing - Wideband Signal Signal Perfect Match Replica Large Peak Very Accurate Timing Detection Threshold Response

38 Robust acoustic data telemetry Header wideband signal - correlation gives very low false alarm rate - hence noise immunity - very good timing sync Data content encoded using proprietary signals - auto compression of ASCII - Forward Error Correction gives error-free data - or no data Not a full modem implementation - inefficient for short packet sizes - introduces latency by using training data 5000m achieved at 25kHz IRS Wideband Telemetry Data Packet

39 Tsunameter - New Developments Enhanced pressure sensor measurement electronics and firmware - Continuous power to sensor - Continuous sampling of pressure (15 sec / sample) - NOAA Detection Algorithm applied to samples Additional memory card data back-up storage - 2 years into 128MB MMC card Lower Frequency band ~15kHz (Prevents clashes with MF LBL and USBL systems) 5000m rated housing, (7000m option)

40 Acoustic Study for NIOT Noise level at surface & seabed Transmission loss: - signal attenuation in vertical path - choice of frequency band 15kHz Off-vertical corrections for beam pattern Off-vertical analysis of ray-bending using water column profile data Equipment detection and transmit levels factory checked Sonar Equation gives the Operating Margin (db)

41 Q & A Head Office Sonardyne International Limited T. +44 (0) Blackbushe Business Park F. +44 (0) Yateley, Hampshire, GU46 6GD E. sales@sonardyne.com United Kingdom